I. Field
The present invention relates generally to communication, and more specifically to techniques for recovering data in the presence of noise and interference at a receiver in a wireless communication system.
II. Background
In a wireless communication system, a transmitter typically encodes, interleaves, and modulates (i.e., symbol maps) traffic data to obtain data symbols, which are modulation symbols for data. For a coherent system, the transmitter multiplexes pilot symbols with the data symbols, processes the multiplexed pilot and data symbols to generate a modulated signal, and transmits the signal via a wireless channel. The channel distorts the transmitted signal with a channel response and further degrades the signal with noise and interference.
A receiver receives the transmitted signal and processes the received signal to obtain received symbols. For a coherent system, the receiver typically estimates the channel response with the received pilot symbols and performs coherent demodulation/detection of the received data symbols with the channel response estimates to obtain recovered data symbols, which are estimates of the data symbols transmitted by the transmitter. The receiver then symbol demaps, deinterleaves, and decodes the recovered data symbols to obtain decoded data, which is an estimate of the traffic data sent by the transmitter.
In a typical coherent wireless system, the receiver processes the received pilot symbols once to obtain the channel response estimates and also performs coherent demodulation once on the received data symbols to obtain the recovered data symbols. The receiver then performs symbol demapping, deinterleaving, and decoding on the recovered symbols in accordance with the coding and modulation schemes used for the traffic data. The noise and interference degrade the quality of the recovered data symbols and affect the reliability of the decoded data. There is therefore a need in the art for techniques to recover data in the presence of noise and interference at the receiver in a wireless communication system.